Weight & Mass Review

Weight & Mass Review

What is Mass?

Mass is a measure of the amount of matter in an object. It is symbolized using m or M and the base unit of measurement is Grams (g).

*** The Law of Conservation of Mass states that matter CANNOT be created or destroyed ***

What is Weight?

Weight is the amount of force that gravity has on an object. It is usually denoted by W and the unit of measurement is Newtons (N).

** 1 Newton = .10kg**

Weight is a measurement that is dependent on both gravity and mass. It can vary based on the amount of gravitational pull an object exerts on an object.

Key differences between

Mass & Weight

• Mass is a property of matter. The mass of an object is the same everywhere. Weight depends on the effect of gravity. Weight increases or decreases with higher or lower gravity.

• Mass can never be zero. Weight can be zero if no gravity acts upon an object, as in space.

• Mass is a scalar quantity. It has its own magnitude. Weight is a vector quantity. It has magnitude that is directed toward the center of a gravity well.

Multiple Choice

What is the definition of mass?

• how much something weighs

• a measure of how much matter an object has

• a force of attraction between 2 objects

• a force gravity exerts on a body

Multiple Choice

The measure of the gravitational pull on an object is called:

• weight

• mass

• matter

• volume

• density

Multiple Choice

True or False -

Mass and weight are the exact same thing.

• true

• false

Multiple Choice

An object's mass _________________________ changes.

• always

• never

• sometimes

• kinda

Multiple Choice

The more mass an object has the ___________ weight it will have as a result.

• less

• more

• equal

How Much Do You Weigh on Other Planets?

As earlier explained the weight of an object can change based on the forces of gravity acting on it. For example, the Moon's gravity is approximately 16% of the Earth's gravity. So, a 100 kg astronaut would weigh 16 kg if they stepped on a scale while on the Moon, due to the lower gravitational force.

Calculating Weight

Gravity on other planets is compared to the gravity on Earth and given a value based on that percentage. The gravity of Earth is given a value of 1G and because the gravity of the Moon is 16%, the G-force would be 0.16G. To calculate the weight of an object, you would multiply its mass/weight on Earth to the G-force in the new gravitational field.

Examples

• Object mass = 87g

  Gravity on Jupiter = 2.64G

  Weight on Jupiter: 87 x 2.64 = 229.68g

• Object mass = 0.79g

  Gravity on Mars = 0.39G

  Weight on Jupiter: 0.79 x 0.39 = 0.308g

Multiple Choice

If the MASS of an object on Earth is 18 grams, what would the MASS of the same object be on the Moon?

• 18 g

• 4 g

• 0 g

• 32 g

Multiple Choice

If an object mass is 30 Kg on the Earth, what would be it's weight on Neptune if the gravitational force is 1.15G?

• 98 Kg

• 30 kg

• 26.08 Kg

• 34.5 Kg

Multiple Choice

A child has a mass of 30 Kg on Earth. If the gravity on Moon is 0.16G, what is the weight of the child on Moon?

• 30 Kg

• 180 Kg

• 5 Kg

• 0 Kg